Method for making carbon nanotube film

ABSTRACT

A method for making a carbon nanotube film includes providing an original carbon nanotube film and an angle control unit. The original carbon nanotube film includes a plurality of carbon nanotubes joined end-to-end by van der Waals force, and the angle control unit defines a through hole. A first end of the original carbon nanotube film is converged to form a carbon nanotube wire structure and a carbon nanotube triangle structure having an open angle adjacent to the carbon nanotube wire structure. The carbon nanotube wire structure is passed through the through hole of the angle control unit. The carbon nanotube triangle structure is cut. The carbon nanotube film is also provided.

RELATED APPLICATIONS

This application is a continuation application of U.S. patentapplication Ser. No. 13/437,110, filed on Apr. 2, 2012, entitled,“CARBON NANOTUBE FILM AND METHOD FOR MAKING THE SAME”, which claims allbenefits accruing under 35 U.S.C. § 119 from China Patent ApplicationNo. 201110349846.2, filed on Nov. 8, 2011 in the China NationalIntellectual Property Administration, the disclosure of which isincorporated herein by reference.

BACKGROUND 1. Technical Field

The present disclosure relates to a carbon nanotube film and a methodfor making the carbon nanotube film.

2. Discussion of Related Art

Carbon nanotubes are excellent in electrical conductivity, thermalconductivity, field emission, and electromagnetic shielding. Therefore,preparations of carbon nanotube films have attracted attention.Traditional methods for making carbon nanotube films generally include adirectly growing method, a spraying method, or a Langmuir Blodgettmethod. However, carbon nanotubes in carbon nanotube films made by theabove methods are randomly arranged.

A method for making a carbon nanotube film by a drawing method includesproviding a carbon nanotube array and drawing the carbon nanotube filmfrom the carbon nanotube array along a certain direction. The carbonnanotubes in the carbon nanotube film are orderly arranged, and most ofthe carbon nanotubes are oriented along a single direction. Further,carbon nanotubes substantially being perpendicular to the singledirection are substantially parallel to each other. However, this filmstructure is directional and can be applied in limited configurations.

What is needed, therefore, is to provide a carbon nanotube film with aunique structure and a method for making the same, to overcome the aboveshortages.

BRIEF DESCRIPTION OF THE DRAWINGS

Many aspects of the embodiments can be better understood with referencesto the following drawings. The components in the drawings are notnecessarily drawn to scale, the emphasis instead being placed uponclearly illustrating the principles of the embodiments. Moreover, in thedrawings, like reference numerals designate corresponding partsthroughout the several views.

FIG. 1 is a schematic view of one embodiment of a carbon nanotube film,wherein the carbon nanotube film includes a number of carbon nanotubewires.

FIG. 2 is a schematic view of one of the carbon nanotube wires shown inFIG. 1.

FIG. 3 is a flow chart of one embodiment of a method for making a carbonnanotube film.

DETAILED DESCRIPTION

The disclosure is illustrated by way of example and not by way oflimitation in the figures of the accompanying drawings in which likereferences indicate similar elements. It should be noted that referencesto “an” or “one” embodiment in this disclosure are not necessarily tothe same embodiment, and such references mean at least one.

Referring to FIG. 1, one embodiment of a carbon nanotube film 10 isprovided. The carbon nanotube film 10 includes a first end 11 and asecond end 13. The second end 13 is opposite to the first end 11. Thecarbon nanotube film 10 includes a number of carbon nanotube wires 12and at least one first carbon nanotube 14. The at least one first carbonnanotube 14 is located between and connects adjacent carbon nanotubewires 12.

The carbon nanotube wires 12 fan out from the first end 11 to the secondend 13, such that a distance between adjacent two carbon nanotube wires12 gradually increases from the first end 11 to the second end 13, thusforming an angle defined by the adjacent two carbon nanotube wires 12.Thereby a number of angles are defined by the number of carbon nanotubewires minus one. If the carbon nanotube wires 12 are uniformly dispersedin the carbon nanotube film 10, the angles defined between every twoadjacent carbon nanotube wires 12 are substantially equal. Otherwise, ifthe carbon nanotube wires 12 are randomly arranged, the angles definedbetween two adjacent carbon nanotube wires 12 are different from eachother.

A shape of the first end 11 can be any shape such as a point, a straightline, or a curve shape. A shape of the second end 13 can also be anyshape such as a straight line or a curve shape. The curve shape can bean arc shape, or a polygonal line. The carbon nanotube film 10 includestwo outermost sides. Each of the two outermost sides connects with thefirst end 11 and the second end 13. The two outermost sides define anopen angle α. The open angle α is larger than 0 degrees, and less than180 degrees. In one embodiment, the open angle α is larger than 30degrees, and less than or equal to 120 degrees. In another embodiment,the open angle α is larger than 30 degrees, and less than or equal to 90degrees. If the first end 11 is a straight line or a curve, the openangle α is defined by extending lines of the two outermost sides. In oneembodiment, the carbon nanotube film 10 is pie-shaped, the first end 11is a point, and the second end 13 is arc-shaped, the open angle α isabout 60 degrees.

Referring to FIG. 2, each carbon nanotube wire 12 includes a number ofsuccessive and oriented carbon nanotube segments 124. Each carbonnanotube segment 124 includes a number of second carbon nanotubes 122parallel to each other. The second carbon nanotubes 122 are combined byvan der Waals force therebetween. The carbon nanotube segments 124 canbe joined end-to-end by van der Waals force therebetween at extendingdirections of the second carbon nanotubes 122. In another embodiment,each carbon nanotube wire 12 includes a number of second carbonnanotubes 122. The second carbon nanotubes 122 are substantiallyoriented along a preferred orientation. Most of the second carbonnanotubes 122 in each carbon nanotube wire 12 extend along a samedirection, and are joined end-to-end by van der Waals force. In oneembodiment, the second carbon nanotubes 122 have the same length.

The at least one first carbon nanotube 14 is connected with adjacentcarbon nanotube wires 12 by van der Waals force to form a freestandingstructure. Therefore, the carbon nanotube film 10 has a freestandingstructure. The carbon nanotube film 10 being a freestanding structuremeans that the carbon nanotube film 10 can maintain a film structure ifpart of the carbon nanotube film 10 is located on a supporter. Forexample, when the carbon nanotube film 10 is placed on a frame or twoseparate supporters, the portion of the carbon nanotube film 10suspended between parts of the frame or between the two supporters willmaintain its film structure integrity.

In one embodiment, a number of first carbon nanotubes 14 are locatedbetween adjacent carbon nanotube wires 12. The first carbon nanotubes 14can be joined end-to-end by van der Waals force at different positionsbetween the adjacent carbon nanotube wires 12. In another embodiment,some of the first carbon nanotubes 14 can be located between theadjacent carbon nanotube wires 12 joined at ends of the second carbonnanotubes 122 of the carbon nanotube wire 12, and some of the firstcarbon nanotubes 14 can be separately located at different positions ofthe adjacent carbon nanotube wires 12. In yet another embodiment, thefirst carbon nanotubes 14 can be located at substantially the samepositions between the adjacent carbon nanotubes wires 12.

Referring to FIG. 3, one embodiment of a method for making the carbonnanotube film 10 is provided. The method can include the followingsteps:

S10, providing an original carbon nanotube film 120 including a numberof carbon nanotube wires 12, wherein each carbon nanotube wire 12includes a number of successive and oriented carbon nanotube segments124;

S20, converging a first end of the original carbon nanotube film 120 toform a carbon nanotube wire structure 130;

S30, passing the carbon nanotube wire structure 130 through an anglecontrol unit 140 including an angle control element 142, and convergingthe original carbon nanotube film 12 at the angle control element 142 toform the open angle α by moving the angle control unit 140 relative tothe carbon nanotube wire structure 130 to a predetermined position; and

S40, obtaining the carbon nanotube film 20 with a predetermined shape,such as by cutting the original carbon nanotube film 120 having thepredetermined open angle at the predetermined position.

In step S10, the original carbon nanotube film 120 includes the carbonnanotube wire 12 and at least one carbon nanotube connected betweenadjacent carbon nanotube wires 12. The original carbon nanotube film 120can be obtained by drawing from a carbon nanotube array. The originalcarbon nanotube film 120 can also be prepared and then cut into apredetermined shape.

In one embodiment, the original carbon nanotube film 120 is made by thefollowing steps: S11, providing a carbon nanotube array 110; and S12,pulling out the original carbon nanotube film 120 from the carbonnanotube array 110 using a tool 112.

In step S11, the carbon nanotube array 110 includes a number of carbonnanotubes. In one embodiment, the carbon nanotube array 110 can be asuper-aligned carbon nanotube array. The carbon nanotubes in thesuper-aligned carbon nanotube array are substantially parallel to eachother and perpendicular to a substrate.

The step S12 can further include the sub-steps: selecting one or morecarbon nanotubes having a predetermined width from the carbon nanotubearray 110 using the tool 112; and pulling the selected carbon nanotubesat a uniform speed along a direction to form carbon nanotube segmentsjoined end to end to achieve the uniform original carbon nanotube film120. In step (b), the tool 112 can be adhesive tape, pliers, tweezers,or another tool allowing multiple carbon nanotubes to be gripped andpulled simultaneously. In one embodiment, in the step S12, one end ofthe original carbon nanotube film 120 is connected with the carbonnanotube array 110.

During the pulling process, as the initial carbon nanotube segments aredrawn out, other carbon nanotube segments are also drawn out end to enddue to van der Waals attractive force between ends of adjacent carbonnanotube segments. The drawing process ensures a substantiallycontinuous and uniform carbon nanotube film being formed. Therefore, theoriginal carbon nanotube film 120 includes a number of carbon nanotubewires 12. The carbon nanotube wires 12 in the original carbon nanotubefilm 120 are substantially parallel to each other. The original carbonnanotube film 120 also includes at least one first carbon nanotube 14located between adjacent carbon nanotube wires 12.

In step S20, the first end of the original carbon nanotube film 120 issubstantially parallel to radial directions of the carbon nanotube wires12 in the original carbon nanotube film 120. The carbon nanotube wirestructure 130 can be formed by twisting around the first end of originalcarbon nanotube film 120 clockwise or counterclockwise. If the originalcarbon nanotube film 120 is connected with the carbon nanotube array110, the first end of the original carbon nanotube film 120 is away fromthe carbon nanotube array 110.

In one embodiment, the step S20 can be executed by the following steps:using a mechanical arm hold the adhesive tape 112; clockwise twistingthe side of the original carbon nanotube film 120 connected with theadhesive tape 112 to form the carbon nanotube wire structure 130; andremoving the adhesive tape 112. In other embodiments, the step S20 canalso be performed by removing the adhesive tape 112 first; and thentwisting the original carbon nanotube film 120 to form the carbonnanotube wire structure 130.

The step S30 can include the sub-steps: passing the carbon nanotube wirestructure 130 through the angle control element 142; and controlling therelative movement between the angle control unit 140 and the carbonnanotube wire structure 130, until the carbon nanotube wire structure130 reaches the predetermined position. Wherein distances betweenadjacent carbon nanotube wires 12 gradually decrease from the carbonnanotube array 110 to the angle control element 142. The open angle αformed at the angle control element 142 is defined by two outermostcarbon nanotube wires 12 at the angle control element 142. In oneembodiment, the carbon nanotube wire structure 130 passes through theangle control element 142 at an angle substantially perpendicular to theangle control element 142.

The angle control unit 140 can be a barrier. The angle control element142 can be a through hole or a slot defined in the angle control unit140. A shape of the angle control element 142 can be circle, rectangle,or other polygons. An effective diameter of the angle control element142 is larger than an effective diameter of the carbon nanotube wirestructure 130. The angle control unit 140 can move back and forth alongthe carbon nanotube wire structure 130. The carbon nanotube wirestructure 130 can also move away from the angle control element 142 andcan twist.

During the movement of the carbon nanotube wire structure 130 relativeto the angle control unit 140, the carbon nanotube wire structure 130and the original carbon nanotube film 120 should not contact a surfaceof the angle control unit 140 and adhere to the angle control element142. In one embodiment, the material of the angle control unit 140 andthe angle control element 142 does not adhere to the carbon nanotubewire structure 130 easily. In one embodiment, a moving direction of thecarbon nanotube wire structure 130 is substantially parallel to apulling direction of the original carbon nanotube film 120.

A width of the original carbon nanotube film 120 is larger than theeffective diameter of the angle control element 142. Therefore, thecarbon nanotube wires 12 of the original carbon nanotube film 120 canconverge at the angle control element 142. Part of the original carbonnanotube film 10 can have a triangular shape. As the carbon nanotubewire structure 130 reaches the predetermined position, the distancebetween adjacent carbon nanotube wires 12 gradually decreases along adirection formed by the carbon nanotube wires 12 close to thepredetermined position. When the carbon nanotube wire structure 130reaches the predetermined position, the carbon nanotube wires 12 of theoriginal carbon nanotube film 120 converge at the angle control element142 to form the first end 11 of the carbon nanotube film 10. At the sametime, the open angle α is formed. Because the first end 11 of the carbonnanotube film 10 is formed at the angle control element 142, if theeffective diameter of the angle control element 142 is relatively small,the first end 11 can be considered a point. If the effective diameter ofthe angle control element 142 is relative large, the first end 11 can becut into a desired shape, such as a straight line, a curve, or a brokenline.

The open angle α of the carbon nanotube film 10 can be controlled by theeffective diameter of the angle control element 142, and a space betweena second end of the original carbon nanotube film 120 and the anglecontrol unit 140. The second end of the original carbon nanotube film120 is opposite to the first end of the original carbon nanotube film120, and the second end of the original carbon nanotube film 120 is awayfrom the carbon nanotube wire structure 130 and the angle control unit140. If the original carbon nanotube film 120 is directly drawn from andconnected with the carbon nanotube array 110, the space is a distancebetween the carbon nanotube array 110 and the angle control unit 140.The space is equal to a distance between the angle control unit 140 anda joint between the carbon nanotube array 110 and the original carbonnanotube film 120.

If the effective diameter of the angle control element 142 is keptunchanged, and if the space between the carbon nanotube array 110 andthe angle control unit 140 is larger, the open angle α is smaller. Ifthe space is smaller, the open angle α is larger. If the space betweenthe carbon nanotube array 110 and the angle control unit 140 is fixed,and if the effective diameter of the angle control element 142 isgreater, the open angle α is smaller. If the effective diameter of theangle control element 142 is smaller, the open angle α is larger.

When the original carbon nanotube film 120 is drawn from and connectedwith the carbon nanotube array 110, a step of moving the carbon nanotubewire structure 130 to the predetermined position can be executed bymaking the relative movement between the carbon nanotube wire structure130 and the angle control unit 140. In one embodiment, the carbonnanotube wire structure 130 is fastened, and the angle control unit 140is moved toward the carbon nanotube array 110. In another embodiment,the angle control unit 140 is fixed, and the carbon nanotube wirestructure 130 is pulled away from the carbon nanotube array 110. Inanother embodiment, the angle control unit 140 is drawn toward thecarbon nanotube array 110, and the carbon nanotube wire structure 130 ismoved away from the carbon nanotube array 110.

The step S40 can include the sub-steps: applying the original carbonnanotube film 120 on a carrier; cutting the original carbon nanotubefilm 120 at the angle control element 142 to form the first end 11 ofthe carbon nanotube film 10; and cutting the original carbon nanotubefilm 120 at a location opposite to the first end 11 of the carbonnanotube film 10 to form the second end 13 of the carbon nanotube film.The second end 13 is formed by cutting the original carbon nanotube film120 in a predetermined pattern to form a desired shape. In oneembodiment, the carrier is the angle control unit 140, and the originalcarbon nanotube film 120 can be cut down by using a laser.

In one embodiment, the carbon nanotube film 10 can be made by thefollowing steps:

A carbon nanotube array 110 is provided. The carbon nanotube array 110is a super-aligned carbon nanotube array, and grown on a substrate (notlabeled).

The original carbon nanotube film 120 is drawn from the carbon nanotubearray 110 using a tool such as an adhesive tape 112. During the drawingprocess of the carbon nanotube array 110, an angle between a drawingdirection and a surface of the substrate for growing the carbon nanotubearray 110 is about 5 degrees.

One end of the original carbon nanotube film 120 adhered to the adhesivetape 112 is twisted clockwise into the carbon nanotube wire structure130.

The carbon nanotube wire structure 130 goes through the angle controlelement 142 of the angle control unit 140, and then fixed on a support150. The angle control unit 140 is a circular flat barrier, and theangle control element 142 is a circular through hole. The support 150can move along the drawing direction of the original carbon nanotubefilm 120, thereby moving the carbon nanotube wire structure 130. Thesupport 150 can also rotate around itself.

The support 150 is rotated around itself, and the carbon nanotube wirestructure 130 fixed on the support 150 is wrapped around the support150. The original carbon nanotube film 120 can be continuously drawnfrom the carbon nanotube array 110. At the same time, the angle controlunit 140 is substantially perpendicular to the carbon nanotube wirestructure 130, and moves toward the carbon nanotube array 110. Two sidesof the original carbon nanotube film 120 contact the angle controlelement 142. The two sides of the original carbon nanotube film 120connect the first and second ends of the carbon nanotube film 120. Whenthe open angle α is about 60 degrees at the angle control element 142,the angle control unit 140 stops moving, and the support 150 rotatesaround itself until the original carbon nanotube film 120 issubstantially uniform.

The angle control unit 140 is rotated to lay the original carbonnanotube film 120 with the open angle α of about 60 degrees on a surfaceof the angle control unit 140. The original carbon nanotube film 120 iscut at the angle control element 142 using a laser to form the first end11 of the carbon nanotube film 10. The original carbon nanotube film 120is cut along an edge of the circular-shaped angle control unit 140, toform the second end 13 of the carbon nanotube film 10. The second end 13is arc-shaped. Thus, a pie-shaped carbon nanotube film 10 is formed.Because the diameter of the angle control element 142 is small, thefirst end 11 can be converged into a point.

The carbon nanotube film 10 includes a number of carbon nanotube wires12, and the carbon nanotube wires 12 fan out from the first end 11 tothe send end 13. The space between adjacent two carbon nanotube wires 12gradually increase from the first end 11 to the second end 13.Therefore, the carbon nanotube film 10 has a specific shape, and can beused to culture biological cells with a specific shape.

The method for making the carbon nanotube film 10 accurately controlsthe open angle α. The carbon nanotube film 10 made by theabove-mentioned method is substantially uniform, including a thicknessof the carbon nanotube film 10. In addition, the original carbonnanotube film 120 can be continuously drawn from the carbon nanotubearray 110, and the carbon nanotube film 10 can be continuously produced.Therefore, the method for making the carbon nanotube film 10 can be usedin commercial production of the carbon nanotube film 10.

It is to be understood that the above-described embodiment is intendedto illustrate rather than limit the disclosure. Variations may be madeto the embodiment without departing from the spirit of the disclosure asclaimed. The above-described embodiments are intended to illustrate thescope of the disclosure and not restricted to the scope of thedisclosure.

It is also to be understood that the above description and the claimsdrawn to a method may include some indication in reference to certainsteps. However, the indication used is only to be viewed foridentification purposes and not as a suggestion as to an order for thesteps.

What is claimed is:
 1. A method for making a carbon nanotube film,comprising: providing a carbon nanotube array and an angle control unit,wherein the angle control unit defines a through hole; drawing anoriginal carbon nanotube film from the carbon nanotube array, whereinthe original carbon nanotube film comprises a plurality of carbonnanotubes joined end-to-end by van der Waals force; converging a firstend of the original carbon nanotube film to form a carbon nanotube wirestructure and a carbon nanotube triangle structure having an open angleadjacent to the carbon nanotube wire structure; passing the carbonnanotube wire structure through the through hole of the angle controlunit; adjusting a size of the open angle by moving the angle controlunit relative to the carbon nanotube wire structure; rotating the anglecontrol unit to lay the carbon nanotube triangle structure on a surfaceof the angle control unit; and cutting the carbon nanotube trianglestructure along an edge of the angle control unit.
 2. The method ofclaim 1, the method of converging the first end of the original carbonnanotube film comprises twisting the first end of the original carbonnanotube film.
 3. The method of claim 1, the method of moving the anglecontrol unit relative to the carbon nanotube wire structure comprisesfixing the angle control unit and moving the carbon nanotube wirestructure along a direction away from the carbon nanotube array, suchthat the original carbon nanotube film is continuously pulled out fromthe carbon nanotube array.
 4. The method of claim 3, the method ofmoving the angle control unit relative to the carbon nanotube wirestructure further comprises, moving the carbon nanotube wire structurerelative to the angle control unit substantially parallel to a drawingdirection of the original carbon nanotube film.
 5. The method of claim3, the method of moving the angle control unit relative to the carbonnanotube wire structure further comprises fixing the carbon nanotubewire structure on a support and rotating the support.
 6. The method ofclaim 1, the method of moving the angle control unit relative to thecarbon nanotube wire structure further comprises fixing the carbonnanotube wire structure and moving the angle control unit toward thecarbon nanotube array.
 7. The method of claim 1, wherein the carbonnanotube triangle structure is cut by a laser.
 8. The method of claim 1,wherein the angle control unit is a circular-shaped plate.
 9. A methodfor making a carbon nanotube film, comprising: providing an originalcarbon nanotube film comprising a plurality of carbon nanotubes joinedend-to-end by van der Waals force; converging a first end of theoriginal carbon nanotube film to form a carbon nanotube wire structureand a carbon nanotube triangle structure having an open angle adjacentto the carbon nanotube wire structure; passing the carbon nanotube wirestructure through a through hole of an angle control unit; adjusting asize of the open angle by moving the angle control unit relative to thecarbon nanotube wire structure; rotating the angle control unit to laythe carbon nanotube triangle structure on a surface of the angle controlunit, and cutting the carbon nanotube triangle structure along an edgeof the angle control unit.
 10. The method of claim 9, wherein the anglecontrol unit is a circular-shaped plate.
 11. The method of claim 9,wherein a shape of the through hole is circle or polygons.
 12. A methodfor making a carbon nanotube film, comprising: providing an originalcarbon nanotube film comprising a plurality of carbon nanotubes joinedend-to-end by van der Waals force; converging a first end of theoriginal carbon nanotube film to form a carbon nanotube wire structureand a carbon nanotube triangle structure having an open angle adjacentto the carbon nanotube wire structure; passing the carbon nanotube wirestructure through a through hole of an angle control unit; rotating theangle control unit to lay the carbon nanotube triangle structure on asurface of the angle control unit, and cutting the carbon nanotubetriangle structure along an edge of the angle control unit.
 13. Themethod of claim 12, wherein the angle control unit is a circular-shapedplate.
 14. The method of claim 12, further comprising separating thecarbon nanotube wire structure from the carbon nanotube trianglestructure.
 15. The method of claim 12, further comprising adjusting asize of the open angle after passing the carbon nanotube wire structurethrough the through hole of the angle control unit.
 16. The method ofclaim 12, the method of adjusting the size of the open angle comprisesmoving the angle control unit relative to the carbon nanotube wirestructure.
 17. The method of claim 12, wherein in the process ofrotating the angle control unit, the carbon nanotube wire structure iskept be through the through hole of the angle control unit.
 18. Themethod of claim 12, further comprising cutting the carbon nanotube wirestructure at the through hole of the angle control unit after cuttingthe carbon nanotube triangle structure along the edge of the anglecontrol unit, to form a carbon nanotube film located on the surface ofthe angle control unit.
 19. The method of claim 1, wherein in theprocess of rotating the angle control unit, the carbon nanotube wirestructure is kept be through the through hole of the angle control unit.20. The method of claim 1, further comprising cutting the carbonnanotube wire structure at the through hole of the angle control unitafter cutting the carbon nanotube triangle structure along the edge ofthe angle control unit, to form a carbon nanotube film located on thesurface of the angle control unit.